Chemoattractant cytokines or chemokines are a family of proinflammatory mediators that promote recruitment and activation of leukocytes (e.g, monocytes, lymphocytes, and granulocytes) and also have additional effects on diverse cell types. They can be released by many kinds of tissue cells after activation. Continuous release of chemokines at sites of inflammation mediates the ongoing migration of effector cells in chronic inflammation. The chemokines characterized to date are related in primary structure. They share four conserved cysteines, which form disulfide bonds. Based upon this conserved cysteine motif, the family is divided into two main branches, designated as the C—X—C chemokines (α-chemokines), and the C—C chemokines (β-chemokines), in which the first two conserved cysteines are separated by an intervening residue, or adjacent respectively (Baggiolini, M. and Dahinden, C. A., Immunology Today, 15:127–133 (1994)).
RANTES (Regulated on Activation, Normal T Expressed and Secreted), the macrophage inflammatory proteins 1α. and 1β (MIP-1α. and MIP-1β), and human monocyte chemotactic proteins 1–3 (MCP-1, MCP-2, MCP-3) are members of the C—C chemokine family and have been characterized as chemoattractants and activators of monocytes or lymphocytes. Migration of leukocytes from blood vessels into diseased tissues is important to the initiation of normal disease-fighting inflammatory responses. This process, known as leukocyte recruitment, is also involved in the onset and progression of debilitating and life-threatening chronic inflammatory, allergic inflammatory and autoimmune diseases. Compounds which block leukocyte recruitment to target tissues in inflammatory and autoimmune disease would be a highly effective therapeutic intervention. Abnormal production of chemokines, such as RANTES and MIP-1α have been implicated in a wide range of human acute and chronic inflammatory diseases, including rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, endometriosis and respiratory diseases, such as asthma and allergic disorders. A review of the role of chemokines in allergic inflammation is provided by Kita, H., et al., J. Exp. Med. 183, 2421–2426 (1996). Chemokines and their receptors have been implicated in the pathogenesis of a number of neurological disorders including ischemic stroke, trauma, Alzheimer's disease, multiple sclerosis and cancer.
The chemokine receptors are members of a superfamily of G protein-coupled receptors (GPCR) which share structural features that reflect a common mechanism of action of signal transduction (Gerard, C. and Gerard, N. P., Annu Rev. Immunol., 12:775–808 (1994); Gerard, C. and Gerard, N. P., Curr. Opin. Immunol., 6:140–145 (1994)). The first receptor for the C—C chemokines that was cloned and expressed, binds the chemokines MIP-1α and RANTES. Accordingly, this MIP-1α/RANTES receptor was designated C—C chemokine receptor 1 (also referred to as CCR-1; Neote, K., et al., Cell, 72:415–425 (1993); Horuk, R. et al., WO 94/11504, May 26, 1994; Gao, J.-I. et al., J. Exp. Med., 177:1421–1427 (1993)). Two other receptors have been characterized which bind and/or signal in response to RANTES: CCR3 mediates binding and signaling of chemokines including eotaxin, RANTES, and MCP-3 (Ponath et al., J. Exp. Med., 183:2437 (1996)), and CCR5 binds chemokines including MIP-1α, RANTES, MIP-1β, and MCP-2. (Samson, et al., Biochem. 35: 3362–3367 (1996)).
The CCR5 ligand RANTES is chemotactic for a variety of cell types, including monocytes, eosinophils, and a subset of T-cells. The ability of RANTES to induce the directed migration of monocytes and a memory population of circulating T-cells (Schall, T. et al., Nature, 347:669–71 (1990)) suggests this chemokine and its receptor(s) plays an important role in chronic inflammatory diseases, since these diseases are characterized by destructive infiltrates of T cells and monocytes. Macrophages and microglia also express CCR5 and the expression is upregulated following activation, especially under conditions of tissue damage such as demyelination. Particular diseases or conditions in which RANTES/CCR5 have been implicated include: transplant rejection, multiple sclerosis, arteriosclerosis (the formation of atherosclerotic plaques that lead to heart attacks and stroke), arthritis (particularly osteo- and rheumatoid arthritis), stroke, atopic dermatitis, airway inflammatory disorders such as Rous Sarcoma Virus-induced bronchiolitis, delayed type hypersensitivity (DTH) reactions, glomerular nephritis, asthma, endometriosis (Am J Obstet Gyncol 169(6): 1545–1549), cancers such as breast, cervical, melanoma, lymphoma, myeloma, Hodgkin's disease, and Hairy cell leukemia. (Cancer Research 62; 1093–1102)(Cancer Research 59; 4681–4687)(Clin Can Res. 7:285–289). Small molecule antagonists of CCR5 would have potential therapeutic utility in treating a wide range of disease states.
It has recently been recognized that the human immunodeficiency viruses (HIV) requires a chemokine receptor, most probably CCR5 or CXCR4, as well as the primary receptor CD4 for efficient entry into target cells (Levy, N. Engl. J. Med., 335(20), 1528–1530 (Nov. 14, 1996). The principal cofactor for entry mediated by the envelope glycoproteins of macrophage tropic strains of HIV-1 is CCR-5, a receptor for the chemokines RANTES, MIP-1α, MIP-1β, and MCP-2 (Deng, et al., Nature, 381, 661–666 (1996)). Accordingly, agents which could antagonize the interaction of HIV with chemokine receptors in humans should prevent infection in healthy individuals and slow or halt viral progression in infected patients leading to a viable method for the prevention or treatment of infection by HIV and the prevention or treatment of AIDS and AIDS related syndromes such as HIV dementia.